Sometimes choices are not thought out

In some competitive situations animals can produce random behavior rather than behavior based on prior experience. The anterior cingulate cortex is where strategies based on models of reality and history are generated; switching to random behavior is done by inputs to this part of the brain from the locus coeruleus. This was reported in a recent paper (citation below).

We generally assume that deciding what to do is based on the best guess of what will be the successful thing to do. Why would random behavior ever be better? It would be if the world seemed to change from what it had been and a new model needed to be constructed. Random exploration would be helpful. Or, there is the case of an opponent that is better at the fight. “We find that when faced with a competitor that they cannot defeat by counterprediction, animals switch to a distinct mode of action selection consistent with stochastic choice. In this mode, characterized by highly variable choice sequences, behavior becomes dramatically less dependent on the history of outcomes associated with different actions and becomes independent from the ACC. ” Primates appear to always try counterprediction before using random choice.

The random behaviour is not the product of the ACC system but is generated elsewhere. A mixture of modelling in the ACC and a random overlay seems the normal state with the amount of randomness depending on the confidence in the modelling. It is like a balance between exploitation and exploration set by the performance of the ACC model. “We note that complete abandonment of an internal model and adoption of a fully stochastic behavioral mode is normally maladaptive because of the associated insensitivity to new information. In rats, such a mode appears to be triggered when repeated modeling efforts prove to be ineffective and thus bears a similarity to the condition of learned helplessness thought to follow the sustained experience of the futility of one’s actions. Intriguingly, functional imaging studies in humans have suggested that a chronic reduction in ACC activity might play a role in this disorder .

This arrangement also seems to fit with the ‘deliberate’ errors that happen in well-learned sequences in sports, bird song, and children’s speech. Confidence in the model is occasionally tested.

Here is the abstract:

Behavioral choices that ignore prior experience promote exploration and unpredictability but are seemingly at odds with the brain’s tendency to use experience to optimize behavioral choice. Indeed, when faced with virtual competitors, primates resort to strategic counterprediction rather than to stochastic choice. Here, we show that rats also use history- and model-based strategies when faced with similar competitors but can switch to a “stochastic” mode when challenged with a competitor that they cannot defeat by counterprediction. In this mode, outcomes associated with an animal’s actions are ignored, and normal engagement of anterior cingulate cortex (ACC) is suppressed. Using circuit perturbations in transgenic rats, we demonstrate that switching between strategic and stochastic behavioral modes is controlled by locus coeruleus input into ACC. Our findings suggest that, under conditions of uncertainty about environmental rules, changes in noradrenergic input alter ACC output and prevent erroneous beliefs from guiding decisions, thus enabling behavioral variation.

Tervo, D., Proskurin, M., Manakov, M., Kabra, M., Vollmer, A., Branson, K., & Karpova, A. (2014). Behavioral Variability through Stochastic Choice and Its Gating by Anterior Cingulate Cortex Cell, 159 (1), 21-32 DOI: 10.1016/j.cell.2014.08.037

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